PROJECT SUMMARY The advent of effective antiretroviral therapy (ART) has enabled millions of HIV-infected patients to achieve long-term remission and survival to middle and old age. This increased survival has resulted in development of a variety of comorbidities linked to HIV and/or ART, including metabolic disease, AIDS-defining cancers, and neurocognitive disorders. With respect to metabolic disease in particular, the lipodystrophy associated with early ART regimes has been replaced by an increased incidence of weight gain and altered adipose tissue function as well as increased risk for type-2 diabetes in patients on newer ART formulations. Proposed mechanisms include HIV-induced disruption of gut integrity and translocation of microbial components that can affect tissue targets such as visceral (particularly omental) adipose tissue to generate a state of chronic systemic inflammation that is a well-documented cause of metabolic dysfunction. Another major issue affecting the large population of people living with AIDS is the global epidemic of obesity and diabetes that also affects people prior to their AIDS diagnosis and initiation of ART. Thus, obesity and prediabetes are increasingly a pre-existing condition in people living with AIDS, and is the basis for our overall hypothesis that pre-existing obesity/metabolic disease regulates HIV infection parameters and response to ART and exacerbates adverse metabolic effects through additive or synergistic effects on systemic inflammation. The in-depth investigation of the mechanisms that link pre-existing metabolic disease with metabolic comorbidities of HIV and ART requires preclinical models that enable studies not feasible in human populations. Simian immunodeficiency virus (SIV)/SHIV-infected nonhuman primates (NHP; rhesus macaques) are the primary preclinical model for study of HIV acquisition, effects of ART, and vaccine development. NHPs are also the ideal experimental system for the investigation of pre-existing obesity as it exhibits an obesogenic response to a western-style diet that mirrors human consumption patterns and is thus an inherently translational model for human diet-induced obesity and metabolic dysfunction. We propose to merge these two unique NHP models to mimic the state of affairs in the human population and to address our hypothesis through pursuit of the following specific aims. Specific aim 1. Determine viral and immunological parameters in lean and obese subjects during SIV challenge and subsequent ART. Specific aim 2. Perform comprehensive systemic metabolic profiling in lean and obese subjects during SIV challenge and subsequent ART. Specific aim 3. Determine tissue-specific differences in SIV-infected lean and obese subjects before and during ART.